Other Investments - Summary of Other Investments (Details) - USD ($) $ in Thousands		Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Investment [Line Items]
Servicing asset, fair value		$ 204,946		$ 286,778
Loan Held-for-investment, Amount		0		39,703
Other Investments	[1]	347,707		438,518
5 Arches, LLC
Investment [Line Items]
Investment in 5 Arches		0		10,754
Mortgage servicing rights
Investment [Line Items]
Servicing asset, fair value		39,837	$ 47,396	60,281	$ 63,785	$ 64,674	$ 63,598
Investment in multifamily loan fund
Investment [Line Items]
Loan Held-for-investment, Amount		32,158		0
Home appreciation options
Investment [Line Items]
Loan Held-for-investment, Amount		11,372		0
Other
Investment [Line Items]
Loan Held-for-investment, Amount		8,812		0
Residential Loans
Investment [Line Items]
Servicing asset, fair value		222,591		300,468
Excess MSRs
Investment [Line Items]
Servicing asset, fair value		$ 32,937		$ 27,312

[1] Our consolidated balance sheets include assets of consolidated variable interest entities (“VIEs”) that can only be used to settle obligations of these VIEs and liabilities of consolidated VIEs for which creditors do not have recourse to Redwood Trust, Inc. or its affiliates. At September 30, 2019 and December 31, 2018, assets of consolidated VIEs totaled $9,596,537 and $6,331,191, respectively. At September 30, 2019 and December 31, 2018, liabilities of consolidated VIEs totaled $8,582,595 and $5,709,807, respectively. See Note 4 for further discussion.